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LICHEN Roccella.

Dyers Lichen, or Orchall.

CRYPTOGAM IA Alga.

Gen. Char, Male, scattered warts.

Female, smooth shields or tubercles, in which thefeeds are imbedded.

Spec. Char. Shrubby, solid, cylindrical, withoutleaves, but little branched. Tubercles alternate,powdery.

Syn. Lichen Roccella. Linn. Sp. PI. 1622. Dicks.Crypt.safe. 3. 19. Smith’s 'Tour, v. 1. 198.

Coralloides corniculatum fasciculate tinctorium, Fuciteretis facie. Dill. Muse. 120. t. 17./. 39.

M R. DICKS ON has lately admitted this Lichen as aBritish native, on the authority of Mr. Gosselin, who found itin Guernsey. Our specimen was gathered by Lord ViscountLewilham on Portland Island. It grows on maritime rocks, verycommon in the Mediterranean and the Levant. Linnæus hadit too from China .

Its solid base is firmly fixed to the rocks, and produces athick tuft of worm-like stems, round, acutely pointed, oftencurved, more or less branched, smooth, os a white, gray orbrownisli hue, and studded about their upper part with scat-tered tubercles, replete with white powder, which some havethought the seeds. Dillenius seems to think these tuberclesmay be only the spots where scutellæ have stood ; in fact, thefructification of this species is not well known.

As an article of commerce it is of very great importance,being extremely valuable for dyeing wool or silk any shade ofpurple or crimson. For this purpose it is steeped in volatilealkali, commonly distilled from urine. Dillenius mentions 80I.sterling per ton as a great price for Orchall, being almost asmuch again as it cost in the Archipelago , so much better ajudge was he of Lichens than of the comfortable emolumentsof trade ! It has since been sold at xoool. in times of scarcity.